Lens system for micro film

ABSTRACT

A lens system for micro film which provides high resolution over a wide range with an ultraviolet ray, and has transmittance sufficient for said ray and a long working distance on the image side. Said lens system comprises a first negative cemented doublet component, a second positive lens component, a third positive lens component, a fourth positive lens component, a fifth positive lens component, a sixth negative cemented doublet component, a seventh negative meniscus lens component, an eighth cemented meniscus lens component and a ninth positive meniscus lens component.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a high resolution lens system for micro film.

(b) Description of the Prior Art

Though light sources emitting visible rays have conventionally been used for photographing on micro films, it is now demanded to photograph reduced images with higher resolution. Examinations made to meet such a demend have indicated that it is possible to photograph reduced images with higher resolution by using a light source emitting rays of higher energy and a sensitive material assuring higher resolution. Speaking concretely, rays emitted from a mercury lamp contains a line of 3650 A which has very high energy. By using this line in combination with such a sensitive material as mentioned above, resolution can be enhanced up to 1μ.

However, the above-mentioned line has a short wavelength, thereby restricting use of glass material having high refractive index which reduces transmittance. It is therefore very difficult to design a lens system having high resolution.

SUMMARY OF THE INVENTION

A general object of the present invention is to provide a lens system for micro film which has high resolution over a wide range with ultraviolet ray of approximately 3650 A, transmittance sufficient for said ray and a long working distance on the image side.

The lens system for micro film according to the present invention comprises a first negative cemented doublet component, a second positive lens component, a third positive lens component, a fourth positive lens component, a fifth positive lens component, a sixth negative cemented doublet component, a seventh negative meniscus lens component, an eighth cemented meniscus doublet component and a ninth positive meniscus lens component. Said lens system is so designed as to satisfy the following conditions:

(1) -14f<r₇ <-11f

(2) 0.31f<r₁₄ <0.35f

(3) -1.2f<r₁₅ <-0.8f

(4) -2.1f<r₁₆ <-2.0f

wherein the reference symbols represent as defined below:

r₇, r₁₄, r₁₅ and r₁₆ : radii of curvature on the image side surface of the third lens component, the image side surface of the sixth lens component and the surfaces on both the sides of the seventh lens component

f: focal length of the entire lens system as a whole

Now, significance of the above-mentioned conditions will be described consecutively. The condition (1) is defined for correcting coma effectively. If radius of curvature r₇ is smaller than the lower limit of this condition, coma will be undercorrected. If r₇ is larger than the upper limit of the conditions (1), astigmatism will be overcorrected.

The condition (2) is required for correcting curvature of field effectively. If r₁₄ is smaller than the lower limit of the condition (2), curvature of field will be overcorrected. If r₁₄ exceeds the upper limit of the condition (2), in contrast, curvature of field will be undercorrected. The condition (3) is necessary for correcting spherical aberration and astigmatism effectively. If r₁₅ is smaller than the lower limit of the condition (3), spherical aberration will be undercorrected. If r₁₅ exceeds the upper limit of the condition (3), distortion will be aggravated and, in addition, astigmatism will be overcorrected.

The condition (4) is effective for favorably correcting distortion. Distortion will be undercorrected if r₁₆ is smaller than the lower limit of the condition (4), whereas astigmatism will be aggravated if r₁₆ is larger than the upper limit of the condition (4).

In addition, the cemented surface of the eighth lens component should preferably be concave on the image side, and the second through fifth positive lens components are so composed as to refract rays gradually.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view illustrating the composition of the Embodiment 1;

FIG. 2 shows curves illustrating the aberration characteristics of the Embodiment 1;

FIG. 3 shows graphs illustrating the OTF characteristics of the Embodiment 1;

FIG. 4 illustrates a sectional view showing the composition of the Embodiment 2;

FIG. 5 illustrates graphs showing the aberration characteristics of the Embodiment 2; and

FIG. 6 illustrates curves showing the OTF characteristics of the Embodiment 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, some preferred embodiments of the present invention will be described with reference to the accompanying drawings.

    ______________________________________                                         Embodiment 1                                                                   f =        1.0       β = 1/10                                                                               N.A = 0.30                                   ______________________________________                                         r.sub.1 = -1.6918                                                              d.sub.1 =  0.3359    n.sub.1 = 1.50405                                                                           ν.sub.1 = 70.15                           r.sub.2 = -2.5058                                                              d.sub.2 =  0.1679    n.sub.2 = 1.67357                                                                           ν.sub.2 = 35.70                           r.sub.3 = 7.4793                                                               d.sub.3 =  1.3684                                                              r.sub.4 = 34.4297                                                              d.sub.4 =  0.2749    n.sub.3 = 1.64083                                                                           ν.sub.3 = 56.36                           r.sub.5 = -2.9883                                                              d.sub.5 =  0.0084                                                              r.sub.6 = 2.5689                                                               d.sub.6 =  0.3594    n.sub.4 = 1.64083                                                                           ν.sub.4 = 56.36                           r.sub.7 = -13.5736                                                             d.sub.7 =  0.0041                                                              r.sub.8 = 1.2594                                                               d.sub.8 =  0.2603    n.sub.5 = 1.64083                                                                           ν.sub.5 = 56.36                           r.sub.9 = 2.4748                                                               d.sub.9 =  0.0041                                                              r.sub.10 = 0.9243                                                              d.sub.10 = 0.2314    n.sub.6 = 1.64083                                                                           ν.sub.6 = 56.36                           r.sub.11 = 1.1089                                                              d.sub.11 = 0.0041                                                              r.sub.12 = 0.7576                                                              d.sub.12 = 0.2939    n.sub.7 = 1.58016                                                                           ν.sub.7 = 58.62                           r.sub.13 = 4.9475                                                              d.sub.13 = 0.1259    n.sub.8 = 1.67357                                                                           ν.sub.8 = 35.70                           r.sub.14 = 0.3169                                                              d.sub.14 = 0.3421                                                              r.sub.15 = -0.8299                                                             d.sub.15 = 0.1446    n.sub.9 = 1.67357                                                                           ν.sub.9 = 35.70                           r.sub.16 = -2.0211                                                             d.sub.16 = 0.0330                                                              r.sub.17 = -2.4178                                                             d.sub.17 = 0.0715    n.sub.10 = 1.54930                                                                          ν.sub.10 = 50.84                          r.sub.18 = 0.4300                                                              d.sub.18 = 0.1572    n.sub.11 = 1.66596                                                                          ν.sub.11 = 60.25                          r.sub.19 = -0.8009                                                             d.sub.19 = 0.0278                                                              r.sub.20 = 0.4379                                                              d.sub.20 = 0.2079    n.sub.12 = 1.50405                                                                          ν.sub.12 = 70.15                          r.sub.21 = 0.8048                                                              ______________________________________                                         Embodiment 2                                                                   f =        1.0       β = 1/10                                                                               N.A = 0.30                                   ______________________________________                                         r.sub.1 = -1.7856                                                              d.sub.1 =  0.2148    n.sub.1 = 1.64089                                                                           ν.sub.1 = 42.32                           r.sub.2 = 1.2886                                                               d.sub.2 =  0.3436    n.sub.2 = 1.64083                                                                           ν.sub.2 = 56.36                           r.sub.3 = -38.9024                                                             d.sub.3 =  1.3916                                                              r.sub.4 = 41.5498                                                              d.sub.4 =  0.2792    n.sub.3 = 1.64083                                                                           ν.sub.3 = 56.36                           r.sub.5 = -3.4487                                                              d.sub.5 =  0.0086                                                              r.sub.6 = 2.5150                                                               d.sub.6 =  0.3651    n.sub.4 = 1.64083                                                                           ν.sub.4 = 56.36                           r.sub.7 = -11.3553                                                             d.sub.7 =  0.0041                                                              r.sub.8 = 1.4984                                                               d.sub.8 =  0.2645    n.sub.5 = 1.64083                                                                           ν.sub.5 = 56.36                           r.sub.9 = 2.7450                                                               d.sub.9 =  0.0041                                                              r.sub.10 = 1.0711                                                              d.sub.10 = 0.2350    n.sub.6 = 1.64083                                                                           ν.sub.6 = 56.36                           r.sub.11 = 1.3387                                                              d.sub.11 = 0.0041                                                              r.sub.12 = 0.8123                                                              d.sub.12 = 0.3942    n.sub.7 = 1.58016                                                                           ν.sub.7 = 58.62                           r.sub.13 = -3.4653                                                             d.sub.13 = 0.0828    n.sub.8 = 1.67357                                                                           ν.sub.8 = 35.70                           r.sub.14 = 0.3485                                                              d.sub.14 = 0.2898                                                              r.sub.15 = -1.1694                                                             d.sub.15 = 0.1469    n.sub.9 = 1.67357                                                                           ν.sub.9 = 35.70                           r.sub.16 = -2.0685                                                             d.sub.16 = 0.0335                                                              r.sub.17 = -1.9939                                                             d.sub.17 = 0.0726    n.sub.10 = 1.54930                                                                          ν.sub.10 = 50.84                          r.sub.18 = 0.4560                                                              d.sub.18 = 0.1597    n.sub.11 = 1.66596                                                                          ν.sub.11 = 60.25                          r.sub.19 = -0.8228                                                             d.sub.19 = 0.0282                                                              r.sub.20 = 0.4608                                                              d.sub.20 = 0.2804    n.sub.12 = 1.50405                                                                          ν.sub.12 = 70.15                          r.sub.21 = 0.6119                                                              ______________________________________                                    

wherein the reference symbols r₁ through r₂₁ represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d₁ through d₂₀ designate thicknesses of the respective lens elements and the airspaces therebetween, the reference symbols n₁ through n₁₂ denote refractive indices of the respective lens elements for the line at a wavelength of 3650 A, the reference symbols ν₁ through ν₁₂ represent Abbe's numbers of the respective lens elements for the d line.

Of the embodiments described above, the Embodiment 1 has such a composition as shown in FIG. 1 wherein the cemented surface r₂ of the first lens component is concave on the object side and the cemented surface of the sixth lens component is concave on the image side. The aberration characteristics and OTF characteristics at a wavelength of 3650 A of this embodiment are illustrated in FIG. 2 and FIG. 3 respectively. The Embodiment 2 has such a composition as shown in FIG. 2 wherein the cemented surface r₂ of the first lens component is concave on the image side and the cemented surface r₁₃ of the sixth lens component is concave on the object side. The aberration characteristics and the OTF characteristics of this embodiment are illustrated also for the line at wavelength of 3650 A in FIG. 5 and FIG. 6 respectively. Seidel's coefficients of these embodiments are as listed below:

    ______________________________________                                         Embodiment 1                                                                         A.sub.ν                                                                             B.sub.ν                                                                              Γ.sub.ν                                                                       P.sub.ν                                                                            □.sub.ν                    ______________________________________                                         1     -0.0081 0.0423   -0.2199 -0.2102                                                                               2.2346                                   2     0.0003  -0.0022  0.0158  -0.0285                                                                               0.0922                                   3     -0.1397 0.0232   -0.0039 -0.0571                                                                               0.0102                                   4     0.1670  0.0262   0.0041  0.0120 0.0025                                   5     0.0314  -0.0667  0.1415  0.1387 -0.5945                                  6     0.2370  -0.0338  0.0048  0.1613 -0.0237                                  7     0.1407  -0.2769  0.5448  0.0305 -0.1322                                  8     0.0757  -0.0109  0.0016  0.3291 -0.0478                                  9     0.0515  -0.1631  0.5165  -0.1675                                                                               -1.1051                                  10    -0.1287 -0.0320  -0.0080 0.4484 0.1096                                   11    0.0099  -0.0732  0.5390  -0.3738                                                                               -1.2169                                  12    -0.0573 -0.0970  -0.1641 0.5143 0.5926                                   13    -0.2417 0.2798   -0.3239 0.0076 0.3661                                   14    0.0188  0.0188   0.0188  -1.3477                                                                               -1.3308                                  15    -0.3403 0.3701   -0.4025 -0.5147                                                                               0.9976                                   16    0.0783  -0.1760  0.3959  0.2113 -1.3659                                  17    -0.0598 0.1429   -0.3417 -0.1556                                                                               1.1888                                   18    -0.0001 -0.0011  -0.0113 0.1116 1.0019                                   19    0.1502  0.0120   0.0010  0.5297 0.0425                                   20    -0.0070 0.0756   -0.8177 0.8122 0.0595                                   21    0.0280  -0.0573  0.1173  -0.4419                                                                               0.6644                                   Σ                                                                              0.0060  0.0006   0.0084  0.0098 0.5457                                   ______________________________________                                         Embodiment 2                                                                         A.sub.ν                                                                             B.sub.ν                                                                              Γ.sub.ν                                                                       P.sub.ν                                                                            □.sub.ν                    ______________________________________                                         1     -0.0069 0.0375   -0.2045 -0.2376                                                                               2.4132                                   2     -0.0001 0.0001   -0.0001 -0.0000                                                                               0.0002                                   3     -0.0321 -0.0298  -0.0277 0.0109 -0.0156                                  4     0.0724  0.0429   0.0254  0.0102 0.0211                                   5     0.0174  -0.0440  0.1116  0.1230 -0.5949                                  6     0.1579  0.0013   0.0000  0.1687 0.0014                                   7     0.1467  -0.2960  0.5973  0.0374 -1.2807                                  8     -0.0140 -0.0047  -0.0016 0.2832 0.0944                                   9     0.0366  -0.1299  0.4615  -0.1546                                                                               -1.0899                                  10    -0.0607 -0.0497  -0.0408 0.3961 0.2912                                   11    0.0191  -0.1031  0.5563  -0.3169                                                                               -1.2919                                  12    -0.0406 -0.0831  -0.1700 0.4910 0.6566                                   13    -0.2637 0.2661   -0.2685 -0.0111                                                                               0.2822                                   14    0.0304  0.0543   0.0969  -1.2546                                                                               -2.0676                                  15    -0.2069 0.3046   -0.4483 -0.3739                                                                               1.2103                                   16    0.0803  -0.1739  0.3768  0.2114 -1.2746                                  17    -0.0677 0.1434   -0.3039 -0.1932                                                                               1.0535                                   18    -0.0002 -0.0020  -0.0235 0.1077 0.9671                                   19    0.1371  0.0141   0.0014  0.5278 0.0542                                   20    -0.0075 0.0769   -0.7871 0.7900 -0.0303                                  21    0.0087  -0.0234  0.0631  -0.5950                                                                               1.4326                                   Σ                                                                              0.0062  0.0012   0.0144  0.0012 0.8323                                   ______________________________________                                     

I claim:
 1. A lens system for micro film comprising a first negative cemented doublet lens component, a second positive lens component, a third positive lens component, a fourth positive lens component, a fifth positive lens component, a sixth negative cemented doublet lens component, a seventh negative meniscus lens component, an eighth cemented doublet meniscus lens component and a ninth positive meniscus lens component, and said lens system satisfying the following conditions:(1) -14f<r₇ <-11f (2) 0.31f<r₁₄ <0.35f (3) -1.2f<r₁₅ <-0.8f (4) -2.1f<r₁₆ <-2.0fwherein the reference symbols r₇, r₁₄, r₁₅ and r₁₆ represent radii of curvature on the image side surface of the third lens component, the image side surface of the sixth lens component, the object side surface and the image side surface of the seventh lens component, and the reference symbol f designates focal length of the entire lens system as a whole.
 2. A lens system for micro film according to claim 1 having the following numerical data:

    ______________________________________                                         f =        1.0       β = 1/10                                                                               N.A = 0.30                                   ______________________________________                                         r.sub.1 = -1.6918                                                              d.sub.1 =  0.3359    n.sub.1 = 1.50405                                                                           ν.sub.1 = 70.15                           r.sub.2 = -2.5058                                                              d.sub.2 =  0.1679    n.sub.2 = 1.67357                                                                           ν.sub.2 = 35.70                           r.sub.3 = 7.4793                                                               d.sub.3 =  1.3684                                                              r.sub.4 = 34.4297                                                              d.sub.4 =  0.2749    n.sub.3 = 1.64083                                                                           ν.sub.3 = 56.36                           r.sub.5 = -2.9883                                                              d.sub.5 =  0.0084                                                              r.sub.6 = 2.5689                                                               d.sub.6 =  0.3594    n.sub.4 = 1.64083                                                                           ν.sub.4 = 56.36                           r.sub.7 = -13.5736                                                             d.sub.7 =  0.0041                                                              r.sub.8 = 1.2594                                                               d.sub.8 =  0.2603    n.sub.5 = 1.64083                                                                           ν.sub.5 = 56.36                           r.sub.9 = 2.4748                                                               d.sub.9 =  0.0041                                                              r.sub.10 = 0.9243                                                              d.sub.10 = 0.2314    n.sub.6 = 1.64083                                                                           ν.sub.6 = 56.36                           r.sub.11 = 1.1089                                                              d.sub.11 = 0.0041                                                              r.sub.12 = 0.7576                                                              d.sub.12 = 0.2939    n.sub.7 = 1.58016                                                                           ν.sub.7 = 58.62                           r.sub.13 = 4.9475                                                              d.sub.13 = 0.1259    n.sub.8 = 1.67357                                                                           ν.sub.8 = 35.70                           r.sub.14 = 0.3169                                                              d.sub.14 = 0.3421                                                              r.sub.15 = -0.8299                                                             d.sub.15 = 0.1446    n.sub.9 = 1.67357                                                                           ν.sub.9 = 35.70                           r.sub.16 = -2.0211                                                             d.sub.16 = 0.0330                                                              r.sub.17 = -2.4178                                                             d.sub.17 = 0.0715    n.sub.10 = 1.54930                                                                          ν.sub.10 = 50.84                          r.sub.18 = 0.4300                                                              d.sub.18 = 0.1572    n.sub.11 = 1.66596                                                                          ν.sub.11 = 60.25                          r.sub.19 = -0.8009                                                             d.sub. 19 =                                                                               0.0278                                                              r.sub.20 = 0.4379                                                              d.sub.20 = 0.2079    n.sub.12 = 1.50405                                                                          ν.sub.12 = 70.15                          r.sub.21 = 0.8048                                                              ______________________________________                                    

wherein the reference symbol f represents focal length of the entire lens system as a whole, the reference symbols r₁ through r₂₁ designate radii of curvature on the surfaces of the respective lens elements, the reference symbols d₁ through d₂₀ denote thicknesses of the respective lens elements and the airspaces therebetween, the reference symbols n₁ through n₁₂ represent refractive indices of the respective lens element for a line at a wavelength of 3650 A and the reference symbols ν₁ through ν₁₂ represent Abbe's numbers of the respective lens elements for the d line.
 3. A lens system for micro film according to claim 1 having the following numerical data:

    ______________________________________                                         f =        1.0       β = 1/10                                                                               N.A = 0.30                                   ______________________________________                                         r.sub.1 = -1.7856                                                              d.sub.1 =  0.2148    n.sub.1 = 1.64089                                                                           ν.sub.1 = 42.32                           r.sub.2 = 1.2886                                                               d.sub.2 =  0.3436    n.sub.2 = 1.64083                                                                           ν.sub.2 = 56.36                           r.sub.3 = -38.9024                                                             d.sub.3 =  1.3916                                                              r.sub.4 = 41.5498                                                              d.sub.4 =  0.2792    n.sub.3 = 1.64083                                                                           ν.sub.3 = 56.36                           r.sub.5 = -3.4487                                                              d.sub.5 =  0.0086                                                              r.sub.6 = 2.5150                                                               d.sub.6 =  0.3651    n.sub.4 = 1.64083                                                                           ν.sub.4 = 56.36                           r.sub.7 = -11.3553                                                             d.sub.7 =  0.0041                                                              r.sub.8 = 1.4984                                                               d.sub.8 =  0.2645    n.sub.5 = 1.64083                                                                           ν.sub.5 = 56.36                           r.sub.9 = 2.7450                                                               d.sub.9 =  0.0041                                                              r.sub.10 = 1.0711                                                              d.sub.10 = 0.2350    n.sub.6 = 1.64083                                                                           ν.sub.6 = 56.36                           r.sub.11 = 1.3387                                                              d.sub.11 = 0.0041                                                              r.sub.12 = 0.8123                                                              d.sub.12 = 0.3942    n.sub.7 = 1.58016                                                                           ν.sub.7 = 58.62                           r.sub.13 = -3.4653                                                             d.sub.13 = 0.0828    n.sub.8 = 1.67357                                                                           ν.sub.8 = 35.70                           r.sub.14 = 0.3485                                                              d.sub.14 = 0.2898                                                              r.sub.15 = -1.1694                                                             d.sub.15 = 0.1469    n.sub.9 = 1.67357                                                                           ν.sub.9 = 35.70                           r.sub.16 = -2.0685                                                             d.sub.16 = 0.0335                                                              r.sub.17 = -1.9939                                                             d.sub.17 = 0.0726    n.sub.10 = 1.54930                                                                          ν.sub.10 = 50.84                          r.sub.18 = 0.4560                                                              d.sub.18 = 0.1597    n.sub.11 = 1.66596                                                                          ν.sub.11 = 60.25                          r.sub.19 = - 0.8228                                                            d.sub.19 = 0.0282                                                              r.sub.20 = 0.4608                                                              d.sub.20 = 0.2804    n.sub.12 = 1.50405                                                                          ν.sub.12 = 70.15                          r.sub.21 = 0.6119                                                              ______________________________________                                    

wherein the reference symbol f represents focal length of the entire lens system as a whole, the reference symbols r₁ through r₂₁ designate radii of curvature on the surfaces of the respective lens elements, the reference symbols d₁ through d₂₀ denote thicknesses of the respective lens elements and the airspaces therebetween, the reference symbols n₁ through n₁₂ represent refractive indices of the respective lens element for a line at a wavelength of 3650 A and the reference symbols ν₁ through ν₁₂ represent Abbe's numbers of the respective lens elements for the d line. 